Aromatic compounds such as phenols and benzene carboxylic acids find many applications in the chemical industry. Benzene dicarboxylic acids and their derivatives, e.g. ortho-phthalic acid (also referred to herein as phthalic acid), meta-phthalic acid (also referred to herein as isophthalic acid) and para-phthalic acid (also referred to herein as terephthalic acid) and their esters, are for instance used on large scale for the production of plasticizers, synthetic fibers, (plastic) bottles, in particular PET bottles, fire-retardant materials, (polyester) resins and the like. Phenols are used as raw materials and additives for industrial purposes in for instance laboratory processes, chemical industry, chemical engineering processes, wood processing, plastics processing and production of polycarbonates. Currently, commercialized processes for the preparation of phenols and benzene dicarboxylic acids typically involve the oxidation of hydrocarbons that are based on fossil fuels such as cumene (for phenol) naphtalene or ortho-xylene (for phthalic acid), m-xylene (for isophthalic acid) and p-xylene (for terephthalic acid).
It is desirable that the production processes of phenols and benzene carboxylic acids, such as respectively phenol, benzene dicarboxylic acids and tricarboxylic acids such as hemimellitic and trimellitic acid/anhydride, that are currently based on using chemicals from fossil feedstocks are replaced or complemented with bio-based production processes, i.e. processes for which the required chemicals originate from a biomass feedstock. Typically, biomass that is suitable for production of chemicals comprises one or more of the following components: oils, fats, lignin, carbohydrate polymers (e.g. starch, cellulose, hemicellulose, pectin, inulin), sucrose, sugar alcohols (e.g. erythritol).
These components can be converted into building blocks for further processing. For instance, carbohydrates can be converted into furanic compounds that may serve as a starting point for the production of phenols, benzenecarboxylic acids and phthalic acids.
A current research aim is providing a process for the large-scale production of phenols or benzene carboxylic acids from renewable feedstock, in particular from lignocellulose-based materials. A first step may be breaking down biomass into lignin, cellulose and hemicellulose, followed by e.g. hydrolysis of the cellulose and dehydration of the obtained sugar to provide furanic compounds. The catalytic dehydration of in particular C5 sugars generally yields furfural and catalytic dehydration of C6 sugars may yield 5-hydroxymethylfurfural (also known as 5-(hydroxymethyl)-2-furaldehyde or 5-HMF) or 5-methoxymethylfurfural (also known as 5-(methoxymethyl)-2-furaldehyde or 5-MMF).
The presence of an electron-withdrawing aldehyde group deactivates the furanic compounds for Diels-Alder (DA) reactions such that harsh reaction conditions are typically required. Due to the harsh conditions and also because furfural and 5-HMF are unstable, furfural and 5-HMF tend to easily decompose or polymerize during the reaction procedure. These furanics are therefore typically unsuitable for direct application in Diels-Alder reactions. As such, furanics comprising an electron-withdrawing group are typically first converted to furanics comprising electron-neutral or electron-donating groups (e.g. by decarbonylation of furfural to furan, hydrogenation of furfural to 2-methylfuran (2-MF) and the like) such that they will be more reactive in Diels-Alders reactions and less harsh conditions are required. However, this approach is generally not desired since this brings additional reduction steps prior to, and oxidation steps after, the Diels-Alder reaction.
A reaction of 2-MF and maleic anhydride (MA) is shown in Scheme 1 in Angew. Chem. Int. Ed. 2016, 55, 1368-1371. An intermediate hydrogenation step of the oxabicyclic adduct is used, wherein H2 is consumed to give a hydrogenated DA adduct that is aromatized in a tandem catalytic reaction. However, the latter reaction is aselective and yields a complex mixture of products, and the formation of mono-acids is atom inefficient. Further oxidation of the still present methyl group into a carboxyl group would generally require harsh conditions, as mentioned. It would also involve introducing oxygen atoms, in for instance an AMOCO-type process, from an external source, thereby incurring additional costs.
Another approach to obtain benzene carboxylic acids is decarbonylation of furfural to furan (as mentioned in for example WO 2014/064070), followed by a Diels Alder reaction with MA (as described for example in U.S. 2014/0142279) to give the oxabicyclic adduct, followed by ring opening and dehydration to phthalic acid/anhydride. This reaction is not atom efficient; in particular in the decarbonlylation step where a carbon atom and an oxygen atom are lost. It has limited yield because the oxabicyclic Diels-Alder adduct is susceptible to retro-reaction. This yields furan which is not sufficiently stable to the ring opening/dehydration conditions and thus decomposes. The oxabicyclic adduct can also be hydrogenated and aromatized, as described in Angew. Chem. Int. Ed. 2016, 55, 1368-1371, but the reaction yields a complex mixture of products of which only about 57% is aromatic. Moreover, this reaction involves the same disadvantage that the process comprises hydrogenation and dehydrogenation.
A reaction of furfural-dimethylhydrazone with MA is described in WO 2007/136640, wherein the formed isobenzofuran is further reacted with 3-aminopiperidine-2,6-dione hydrochloride. The reaction is also mentioned in PNAS 112(12) E1471-1479 for the preparation of thalidomide analogues, wherein it is followed by a reaction with rac-3-amino-2,3-dioxopiperidine. The reaction is also mentioned in J. Org. Chem. 49(21) 4099-4101 (1984) and J. Org. Chem. 53(6) 1199-1202 (1988). None of these documents is directed to biomass-derived compounds and the conversion of an aldehyde group of a furanic compound into a hydroxyl, carboxylic group or ester group, to provide phenols, benzene carboxylic acids and/or esters thereof. These are generally bulk chemicals.
Particularly desirable is the production of terephthalic acid from renewable biomass. A process for the production thereof from 2,5-dimethylfuran is given in WO 2014/043468.
The production of phenol or bisphenols is also particularly desirable.